Log Message:
Update libxfce4ui to 4.13.1:

4.13.1
======
- Better Gtk3.20 compatibility (fix XfceHeading style, drop deprecated call)
- Translation updates: Bulgarian, Catalan, Chinese (China), Chinese (Taiwan),
  Croatian, Czech, Danish, Dutch (Flemish), English (Australia), French, German,
  Hebrew, Japanese, Korean, Lithuanian, Norwegian Bokm?l, Polish, Portuguese
  (Brazilian), Russian, Slovak, Spanish, Swedish, Thai, Turkish, Ukrainian